One could be pedantic and say that the article correctly explains why he deserves to be "classified" as the best Scrabble player on Earth.
The very last line says that he knows every legal Scrabble word. The article also claims that he has a "photographic" memory. That's certainly an important skill to have, but can't be the entire reason. Even the strongest Scrabble AI has a worse rating than Richards.
The other aspect that the article mentions is a focus on the current game. Richards is not even interested in games that he has completed.
So, the article does not definitively conclude, but it does offer two significant factors that are significant to the question it proposed.
You are misquoting. "Photographic" is a misnomer because exact images are not recalled. But extensive detailed recollection does exist, as the SA article explains.
